1. Field of the Invention
The present invention relates to an image processing apparatus, an inkjet printing apparatus, and an image processing method, and more particularly, to technology that suppresses uneven glossiness in a printed image using clear inks, which substantially do not contain color material.
2. Description of the Related Art
The technology described in Japanese Patent No. 3591534 is known as a technology that suppresses uneven glossiness. Japanese Patent No. 3591534 describes adjusting the glossiness of a printed image by setting an application amount of clear ink which substantially does not contain color material, on the basis of application amounts of colored inks which do contain color material. According to this technology, when forming an image on a print medium with high glossiness, the clear ink is mainly printed in areas with low amounts of the colored ink, thus making it possible to reduce uneven glossiness.
In addition, Japanese Patent Laid-Open No. 2011-218564 describes a clear ink printing method that executes two printing modes: a first printing mode for common printing that applies clear ink to the same area before completing the application of colored ink; and a second printing mode for after application printing that applies the clear ink to an area after completing the application of the colored ink in that same area. In addition, by switching between these two printing modes, it is possible to realize either an emphasis on uniform glossiness or an emphasis on a dark color gamut.
However, in the case of printing a mixed image containing areas where light inks are mainly used as well as areas where dark inks are mainly used, there is a problem of being unable to effectively suppress uneven glossiness when clear ink is used in the same way across these areas. Furthermore, this problem is difficult to solve even when using the technology described in any of the above literatures.
More specifically, Japanese Patent No. 3591534 merely describes a method of adjusting glossiness according to the amount of colored ink. For this reason, glossiness is simply adjusted with the clear ink according to the respective amounts of colored ink both in areas where light inks are mainly used and in areas where dark inks are mainly used, whereas the relative glossiness among these areas cannot be adjusted. Particularly, it is not possible to solve the problem of the glossiness becoming too strong in the areas where light inks are mainly used.
Meanwhile, Japanese Patent Laid-Open No. 2011-218564 describes differentiating the way of using the clear ink according to the two printing modes, but the way of using the clear ink is determined according to whether or not uniform glossiness is to be emphasized. For this reason, even if the way of using clear ink is differentiated, it is not possible to adjust glossiness between the areas where the light inks are mainly used and the areas where the dark inks are mainly used.